Current cylinders are provided with wall entrance seal units. However, for achieving satisfactory seal, the friction force between the seal and the piston rod envelope surface will be high.
This type of seal units, such as piston rod seals of a cylinder body have been known for a long time. There is at least needed a thin film of clean lubricant fluid between the seal and the piston rod envelope surface. Without such film, the seal will undergo premature wear and consequently unwanted leakage. Thicker lubricant fluid films would cause leakage caused by overflowing fluid lubricant.
Hydraulic equipment in general, and hydraulic cylinders especially, thus leaks hydraulic fluid (e.g. oil) when they are pressurized and actuated.
Many users of actuators choose to use electric or pneumatic actuators for avoiding this problem. They want to avoid having to deal with oil-soaked equipment of both health and environmental reasons.
The applicant of this application has also described different embodiments of an elongated fluid actuator arrangement in the international patent applications PCT/SE2014/050753 and PCT/SE2014/051377, but which is not yet published. The arrangement disclosed in PCT/SE2014/051377 works well, but is subjected to development.
Rubber bellows or boots are installed on devices with ranges of motion to provide protection from dust and particles. Rubber boots reduce the frequency of maintenance and increase the life by protecting the equipment from contamination. Rubber boots per se have been known for a long time. One type of such rubber boot is disclosed in U.S. Pat. No. 4,154,434.
There is an object to provide an elongated fluid actuator arrangement of the type defined in the introduction which is environmental friendly and provides clean working environment.
There is also an object to provide a high actuator speed with low friction and high efficiency of such elongated fluid actuator arrangement. There is an energy aspect associated with overcoming the friction when actuation is wanted. The piston force diminished by friction, when using hydraulic actuators, could be up to 30%. Minimizing this loss is essentially the motivation for many industries dealing with research in friction.
An object of the present invention is to develop an energy saving elongated fluid actuator arrangement providing reliable functionality and/or providing actuator arrangements that can be applied to long distance and extended piston rod members. These are preferably put into use in e.g. lifts and high bay storage arrangements having such extended and relatively long piston rods.
A yet further object is to provide an elongated fluid actuator arrangement that is easy to serve and that involves cost-effective maintenance in service.
An object of the present invention is to develop an energy saving elongated fluid actuator arrangement providing reliable functionality and/or providing actuator arrangements that can be applied to long distance and extended piston rod members. These are preferably put into use in e.g. lifts and high bay storage arrangements having extended and relatively long piston rods.
An object is to improve current fluid actuator arrangements in mobile and industrial applications.
An object is to provide elongated fluid actuator arrangements to accomplish work with only minor amount of input force.
The present invention provides an elongated fluid actuator arrangement that can be used in material handling equipment, agricultural equipment, vehicles, excavators, wellhead and jacking systems, construction equipment, hydraulic presses and others. One aspect is to adapt the arrangement to 3D-printing in plastic, composite and/or metal applications for aircraft or automotive industry. A yet further aspect is to provide an arrangement that can be used in automated storage and retrieval systems for car parking and rough-terrain robots, so called legged robot systems. There is also an object to provide an elongated fluid actuator arrangement that can be used in military equipment utilizing hydraulic and/or pneumatic mechanisms. This includes armoured personnel carriers, aircraft material handlers, cranes and loaders, hook lifts, track adjusters and truck-mounted bridge layers etc.